Five Easy Pieces: The Dynamics of Quarks in Strongly Coupled Plasmas

We revisit the analysis of the drag a massive quark experiences and the wake it creates at a temperature T while moving through a plasma using a gravity dual that captures the renormalisation group runnings in the dual gauge theory. Our gravity dual has a black hole and seven branes embedded via Ouyang embedding, but the geometry is a deformation of the usual conifold metric. In particular the gravity dual has squashed two spheres, and a small resolution at the IR. Using this background we show that the drag of a massive quark receives corrections that are proportional to powers of log T when compared with the drag computed using AdS/QCD correspondence. We use the perturbation produced by the quark strings to compute the wake and compare with the results obtained using AdS/QCD correspondence. We also study the shear viscosity with running couplings, analyze the viscosity to entropy ratio and compare the result with the known bound. In the presence of higher order curvature square corrections from the back-reactions of the embedded D7 branes, we argue the possibility of the entropy to viscosity bound being violated. Finally, we show that our set-up could in-principle allow us to study a family of gauge theories at the boundary by cutting off the dual geometry respectively at various points in the radial direction. All these gauge theories can have well defined UV completions, and more interestingly, we demonstrate that any thermodynamical quantities derived from these theories would be completely independent of the cut-off scale and only depend on the temperature at which we define these theories. Such a result would justify the holographic renormalisabilities of these theories which we, in turn, also demonstrate. We give physical interpretations of these results and compare them with more realistic scenarios.Comment: 130 pages, 12 eps figures, LaTex; v4: final version with corrected typos, numerous additional references and enlargement of some sections. The published version, that appears in Nucl. Phys. B, differs slightly in section 3 where there is more emphasis on holographic renormalisabilty and less on the wake, compared to this versio

Household leverage and mental health fragility

We use detailed administrative records to show that high household leverage increases mental health fragility, with persistent negative economic effects. After adverse life events, e.g. heart attacks or job losses, individuals with higher ex ante leverage experience larger increases in mental health problems. The effects are long-lasting and stronger in times of financial crisis. Parallel pre-trends, robustness to non-parametric controls, and IV estimation suggest the results are not driven by confounding unobservables. High leverage is also associated with worse long-run earnings dynamics at the time when loan arrears and mental health problems emerge, suggesting tenacious scarring effects of leverage

Galaxy angular momentum alignment with filaments at z 3: The effect of large scale structure on galaxies

International audienceWe propose NIRSpec MSA spectroscopy to measure, for the first time, the evolution of the alignment of galaxy angular momentum vectors with the surrounding large-scale filamentary structure in the Universe by measuring it at z~3 and comparing with local measurements. This probes the influence of accretion from the cosmic web on the angular momentum of star-forming galaxies. We will test theory predictions that galaxies should be more aligned with filaments at higher z. Locally, kinematic surveys find that the angular momentum of galaxies is statistically aligned with the cosmic web for late-type star forming galaxies, while orthogonal for early types (e.g., Kraljic et al 2021). We propose a mini-MaNGA-like survey of 250 star-forming galaxies at z~3 in the CEERS ERS field with the G235H grating. We will use the NIRSpec MSA in "slitlet stepping" mode to create high quality sub-kiloparsec 2D IFU-like velocity maps. This allows a high multiplex to obtain many kinematic maps in a modest amount of observing time. We will measure the kinematic major axes to obtain the directions of angular momenta, and correlate these directions with filamentary structure traced by spectroscopic and photometric redshifts. We will also measure the 3D kinematics of typical star-forming galaxies at z~3, extending current observations to higher redshifts, and enabling emission line diagnostic science. We waive the proprietary period and will release data cubes and analysis software publicly